FOR the past four or five years, one theme burned through discussions at the Hay festival in the Welsh market town of Hay-on-Wye more than most climate change, and the large and small things human beings might do to tackle it.

Politicians — including, most famously, Al Gore — arrived here to talk up their ecological credentials, green authors warned the crowds of the doom that may await us, and everyone lapped it up.

Moreover, with the Copenhagen summit coming into view, last year's environmental sessions had an infectious mixture of trepidation and momentum, as they focused on The Big Question whether the governments of the world would congregate and resolve to actually do something.

And then look what happened. Copenhagen turned out to be a grim, acrimonious affair, and the United Nations Framework Convention on Climate Change process now looks dangerously close to stalling. Just before the summit took place, the so-called 'Climategate' affair (when emails at the University Of East Anglia's Climatic Research Unit were hacked, leading to a flurry of accusations about data manipulation) allowed the sceptics a field day.

Immediately afterwards, a dispute about the Intergovernmental Panel on Climate Change's work on melting Himalayan glaciers gave them even more encouragement. Recession and the crisis in public finances, too, seemed to hoof climate change well down the world's list of political priorities — while even this year's bitter winter gave the voices of climate-change denial yet another boost. As a result, this year's green Hay sessions have an ever-so-slightly tortured kind of atmosphere, translatable as “What are we going to do now?”, and are largely devoid of the spurts of tentative optimism that preceded Copenhagen.

On Saturday afternoon, the UK's former Energy and Climate Change secretary — and much-tipped Labour leadership contender — Ed Miliband delivers one of this year's big eco-hits a video-link conversation with the president of the Maldives, the cluster of islands in the Indian Ocean that's already dealing with the grim effects of an overheating planet.

Mohamed Nasheed, 43, came to office after long years of torture and imprisonment; now he's keen to talk about rising sea and freshly evacuated islands, and tell people in the northern hemisphere what's required of them. “What we need is large-scale, 60s-style direct action dynamic street activity,” he says. “We need to act very quickly.” The words rouse the crowd, but there's an uneasiness in the air right now, are large amounts of “dynamic street activity” a realistic possibility?

An hour after the event, I meet Miliband. “When I was here last year,” he says, “I did an event with Franny Armstrong (director of the climate change film The Age Of Stupid). There was high expectation then. Now, there's a sense of” — he slows down, so as to pick his words carefully — “sober reality”.

But I don't think there's a despair. People don't think it's all hopeless. Copenhagen was the crest of a wave, and you inevitably have a bit of a sense of disappointment, and people wanting to gear themselves up again. I think they realise you've got to dig in for a long struggle.

— The Guardian, London